1. Field of the Invention
The present invention relates to the mechanical arts. In particular, it relates to an apparatus and process for defatting meat, the resulting defatted meat, and products containing the resulting defatted meat.
2. Discussion of the Related Art
All meats contain protein (muscle), fat and water. The fat is found not only in cells forming fatty or adipose tissues, but in cells interspersed between muscle tissues. The composition, physical and chemical properties of the fat differs significantly depending on the location of the cells.
In recent years, a great deal of attention has been focused on the dangers of diets high in fat, especially as high fat diets have been implicated in an increased incidence of diseases of blood vessels, such as coronary heart disease and arteriosclerosis. As a consequence of these studies and concerns, the medical profession has been advising that consumption of fat be reduced. One way this can be accomplished is by eating meats that have been processed, so that they contain little, if any, fat.
Processes for removing fat from meat can be viewed as involving two steps. First, a primarily fat-containing fraction must be freed from the meat-containing fraction. Second, the two fractions must be separated from one another.
In the simplest form of fat removal--manually cutting fat from the meat--the two steps are combined. Fat-containing tissue is cut from meat-containing tissue and the resulting fractions are separated by what is essentially the same motion. Unfortunately, manually cutting fat from red meat, for example, is effective in reducing the fat content of the remaining meat fraction to no lower than about five percent. Further, skilled workers and much time are needed to cut the meat, thus making the process expensive.
In an attempt to reduce the fat content of meat other processes have been suggested. These processes typically employ one or more of the following approaches. First, the fat can be freed from meat by mechanical techniques, such as by the use of a grinder, a crusher, a press, a comminuter, or a microcomminuter. These procedures have been employed with or without accompanying high temperatures. Second, physical extraction techniques, such as the use of heat, and reaction of gases with meats, including fluid extraction, have been applied to remove fat from meat. Third, fat has been removed employing chemical extraction techniques, such as the use of chemical reagents, including acids, alkalis, and the like.
Unfortunately, these techniques all suffer from numerous drawbacks. They generally have a detrimental impact on the functionality of the meat or alter the meat's protein profile, vitamin profile, its color, its texture and/or its water content. For example, high temperatures denature meat. The use of diluents, such as water, can leach water-soluble proteins and vitamins from the meat and can increase the moisture content of the defatted product. Additionally, when diluents are used with micro-comminution of meat, the functional properties of the resulting product are adversely affected. And the acid or alkaline treatment of meat facilitates the binding of anions or cations, respectively, to the protein, thereby adversely affecting the meat's functional properties, particularly its solubility characteristics. Consequently, it is a desideratum to defat meat using the mildest possible conditions, i.e., using minimal grinding, little if any added water or added chemical reagents and mild temperatures.
Moreover, it is often the subsequent separation step that is critical to the success or failure of a defatting process. Even if a substantial amount of fat is initially liberated from the meat, unless the fat is effectively separated from the meat, the process will not be a success. For example, even if the proper choice of conditions for grinding or comminuting meat produces a substantial fat-containing fraction, conventional devices, such as conventional decanter centrifuges, are not completely effective in separating the resulting fractions. Accordingly, it is also a desideratum to maximize the effectiveness of the separation fat-containing and meat-containing fractions.
There has also been a long felt need for lowering the cholesterol contained in meat products. Accordingly, it is a desideratum to employ an apparatus and process that not only reduces the level of fat, but also significantly reduces the level of cholesterol in meat.